Breed is associated with the ABCB1-1Δ mutation in Australian dogs

Vincristine Induced Adverse Effects in Lymphoma Bearing Dogs With Asymptomatic Neutropenia at the Time of Drug Administration

Vincristine sulphate, a microtubule inhibitor, is used extensively in veterinary oncology for treating lymphoma. Neutropenia during multiagent protocols is a common reason for treatment delay and reduced dose intensity. This study evaluated toxicities associated with treating systemically well neutropenic lymphoma patients with vincristine. Lymphoma patients undergoing CHOP were evaluated retrospectively for instances of vincristine administration when absolute neutrophil counts (ANC) were 1.5 × 109/L or below. Instances of vincristine administration when ANC was equal to or less than 1.5 × 109/L were compared to vincristine administration where ANC was greater than 1.5 × 109/L in the same patient. Univariate and multivariate modelling compared VCOG-CTCAE v1.1 grading of vomiting, diarrhoea, anorexia and 7-day neutrophil nadir between groups. The median dose of vincristine administered was 0.7 mg/m2 for both study groups. A total of 112 doses of vincristine were administered to neutropenic patients (grade 2 n: 76, grade 3 n: 26, and grade 4 n: 10). These were compared to 223 doses of vincristine administered to the same patients when ANC was above 1.5 × 109/L. Neutropenic administration was most prevalent 7 days following cyclophosphamide administration. Day 7 post-administration neutropenia was more prevalent in patients with ANC greater than 1.5 × 109/L at the time of vincristine administration (neutropenic 9%; non-neutropenic 18%). Relative risk of 7-day neutropenia, vomiting, diarrhoea, and anorexia was similar between groups on multivariate analysis. Patients with lymphoma who receive vincristine when ANC is 1.5 × 109/L or below are at no greater risk of adverse effects than the same patient who receives vincristine when neutrophil counts are greater than 1.5 × 109/L.

The prevalence of the ABCB1-1Δ variant in a clinical veterinary setting: The risk of not genotyping

Multidrug sensitivity is an autosomal recessive disorder in dogs caused by a 4-bp deletion in the ABCB1 gene, often referred to as the ABCB1-1Δ variant. This disease has a high prevalence in some breeds and causes adverse reactions to certain drugs when given in normal doses. Though most dogs known to be at risk are of the collie lineage or were traced back to it, the variant has also been described in several seemingly unrelated breeds. It is generally advised to genotype dogs at risk before treating them. However, there seems to be a discrepancy between the advice and current veterinary practices, as a recent study in Belgium and the Netherlands showed that most veterinarians never order a DNA test. To assess the possible risk of not testing for multidrug sensitivity in a clinical setting, the ABCB1-1Δ variant allele frequency was established in a sample of 286 dogs from a veterinary clinic. This frequency was compared to the allelic frequency in 599 samples specifically sent for genetic testing. While the allelic frequency in the sample for genetic testing was high (21.6%) and in line with the general reports, the allelic frequency in the clinical setting was low (0.2%), demonstrating an enormous difference between laboratory and clinical frequencies. Because of the low frequency of the disease-causing variant in the general clinical population, the risk of encountering a dog displaying multidrug sensitivity despite not genotyping seems to be low. As the variant was only found in an at-risk breed, the current recommendation of routinely genotyping at-risk breeds before treatment seems justified.

Heartworm disease - Overview, intervention, and industry perspective

Dirofilaria immitis, also known as heartworm, is a major parasitic threat for dogs and cats around the world. Because of its impact on the health and welfare of companion animals, heartworm disease is of huge veterinary and economic importance especially in North America, Europe, Asia and Australia. Within the animal health market many different heartworm preventive products are available, all of which contain active components of the same drug class, the macrocyclic lactones. In addition to compliance issues, such as under-dosing or irregular treatment intervals, the occurrence of drug-resistant heartworms within the populations in the Mississippi River areas adds to the failure of preventive treatments. The objective of this review is to provide an overview of the disease, summarize the current disease control measures and highlight potential new avenues and best practices for treatment and prevention.

Single-cell molecular profiling of all three components of the HPA axis reveals adrenal ABCB1 as a regulator of stress adaptation

Chronic activation and dysregulation of the neuroendocrine stress response have severe physiological and psychological consequences, including the development of metabolic and stress-related psychiatric disorders. We provide the first unbiased, cell type-specific, molecular characterization of all three components of the hypothalamic-pituitary-adrenal axis, under baseline and chronic stress conditions. Among others, we identified a previously unreported subpopulation of Abcb1b+ cells involved in stress adaptation in the adrenal gland. We validated our findings in a mouse stress model, adrenal tissues from patients with Cushing's syndrome, adrenocortical cell lines, and peripheral cortisol and genotyping data from depressed patients. This extensive dataset provides a valuable resource for researchers and clinicians interested in the organism's nervous and endocrine responses to stress and the interplay between these tissues. Our findings raise the possibility that modulating ABCB1 function may be important in the development of treatment strategies for patients suffering from metabolic and stress-related psychiatric disorders.